Composite motor cases are fabricated from high strength filaments or tapes such as fiberglass, graphite, poly-p-phenyleneterephthalamide (Kevlar), in a polymeric matrix. The primary mode of failure is due either to poor adhesion between the matrix and the filament or tapes or because of the development of microcracks or microvoids in the matrix. Both of these problems are at least in part related to the fact that when the matrix undergoes polymerization, a pronounced shrinkage in volume takes place. If the matrix were to undergo expansion in dimensions, it would expand onto the irregular surface of the filaments or tapes and into the crevasses and in this manner produce considerably stronger micromechanical adhesion between the matrix and filament or tape.
An object of this invention is to provide composite motor case polymers that expand on polymerization.
Another object of this invention is to provide a matrix formulation for use in a composite motor case wherein the matrix undergoes expansion in dimensions when the matrix composition undergoes polymerization to thereby achieve an expansion onto the irregular surfaces of the filaments or tapes and into the crevasses and in this manner produce considerably stronger micromechanical adhesion between the matrix and filament or tape.